1. Field of the Invention
This invention relates to the control of wax deposition from wax-containing oil, and more particularly to a method for inhibiting the formation of wax deposits in wells, tanks, pipelines, and other equipment used for handling crude petroleum and other wax-containing oils.
2. Description of the Prior Art
It is well known that when a crude petroleum or petroleum fraction containing paraffin wax is cooled below the solidification temperature of the wax, the wax solidifies and tends to deposit on the walls and other surfaces of equipment contacted by the cooled petroleum. The deposition and accumulation of wax-like substances on the walls and other surfaces of equipment contacted by wax-containing petroleum is a major problem in the production, transfer, storage and processing of crude petroleum and petroleum fractions containing significant amounts of wax, since the wax deposits often restrict or completely stop flow through this equipment, requiring costly cleaning to maintain the equipment in operation. More specifically, it is well known that wax-like substances deposit and accumulate on the surfaces of conduits and flow passages of wells operated for the production of wax-containing crude oils and that this wax deposition causes plugging that progressively decreases the rate of production from the well. Also, the wax-like substances deposit in pipelines, vessels and storage tanks handling wax-containing crude oil which results in a serious problem of plugging and clogging this equipment. Furthermore, deposition and accumulation of wax can cause plugging in heat exchangers and malfunctioning of valves in pumps and other apparatus employed in the treating and transportation of wax-containing crude oil and in the refining of such crude oil. The deposition and resulting accumulation of wax in well conduits and transportation, storage and treating equipment reduce the efficiency and capacity of the equipment, often necessitating frequent cleaning to maintain the equipment operational.
Various techniques for inhibiting the deposition of wax from wax-containing oils and for retarding its accumulation in wells and surface equipment have been proposed. Mechanical devices such as scrapers and the like have been employed to maintain the interior surfaces of vessels and well conduits free of wax accumulations, but these devices are both costly and complex, and in many applications are only partially effective in preventing the accumulation of wax since they function by removing wax accumulations already formed rather than preventing the accumulation from forming initially. A method for inhibiting wax deposition is desired that can be practical during normal operation and does not require the shutdown or interruption of these operations. U.S. Pat. No. 3,669,189 issued June 13, 1972 to Fischer teaches the addition to petroleum of a copolymer of ethylene and a monoethylenically unsaturated ester to inhibit wax deposition. This additive has met with some success. However there exists a need for a further improved low cost, practical method for inhibiting the deposition and accumulation of wax from wax-containing petroleum and other wax-containing oils.
Accordingly, a primary object of this invention is to provide a method for inhibiting the deposition of wax from wax-containing petroleum and other wax-containing oils, such as synthetic crude oil and shale oil, particularly those petroleums and oils containing a high concentration of wax.
Another object of the invention is to provide a method for ameliorating the deposition of wax in wells, tanks, pipelines and other equipment handling wax-containing petroleum and liquid petroleum fractions.
Still another object of the invention is to provide a satisfactory technique for producing, storing, and transporting wax-containing crude oils.
A further object of the invention is to provide a method for inhibiting the agglomeration of solid wax particles in a wax-containing crude petroleum.
A still further object of the invention is to provide a method for inhibiting the agglomeration of solid wax crystals in a wax-containing oil.
A yet further object of the invention is to provide a method for removing accumulated wax deposits from equipment handling wax-containing oils, such as synthetic crude oil and shale oil, particularly those petroleums and oils containing a high concentration of wax.
Other objects and advantages of the invention will be apparent from the following description.